Add Windows TOR Client Execution Detected (#3881)

* Add Windows TOR Client Execution Detected

This detection is used to detects the execution of TOR browser and it's components on windows systems.

If you need any further information, please reach out to me via Slack.

Slack ID - Vignesh Subramanian

* Update Windows TOR Client Execution Detection

1. Focused on detecting tor.exe and added the process_path field to detect TOR execution within Brave Browser. 

Brave Browser includes a built-in TOR client that is not explicitly named tor.exe during process creation; instead, it appears as tor-0.4.8.19-win32-brave-0. To capture this, I added the Brave Browser path to the detection logic to identify the presence of TOR within Brave. 

I also introduced wildcards in the path to support any version TOR binaries used by Brave, ensuring that different version numbers are correctly matched. 

2. Avoided using escape characters to improve readability.

3. The provided ID has been added.

4. The process field has been added as a threat object.

5. Additional tokens have been included in the risk-based alerting message to make it clearer and more meaningful.

6. The word “detection” has been removed from the title, which is now: "Windows TOR Client Execution"

7. Added the correct attack dataset link from (https://github.com/splunk/attack_data/blob/master/datasets/attack_techniques/T1090.003/windows_tor_client_execution/windows-sysmon.log)

* Revise Windows TOR Client Execution detection details

Updated the detection configuration for Windows TOR Client Execution, including changes to the description, how to implement, known false positives, and drilldown searches.

---------

Co-authored-by: Nasreddine Bencherchali <nbencher@cisco.com>
Co-authored-by: Nasreddine Bencherchali <nasreddineb@splunk.com>

detections/endpoint/windows_tor_client_execution.yml

@@ -0,0 +1,106 @@
+name: Windows TOR Client Execution
+id: f164bc6f-ecbe-45e0-aaa6-f5c4d8c84b9a
+version: 1
+date: '2026-02-02'
+author: Vignesh Subramanian, Splunk
+status: production
+type: Anomaly
+description: |
+  The following analytic detects the execution of the TOR Browser and related TOR components on Windows endpoints by monitoring process creation activity.
+  Adversaries and insider threats leverage TOR to anonymize command-and-control traffic, facilitate data exfiltration, and evade network monitoring and policy enforcement.
+  While TOR can be used for legitimate research and privacy purposes, its presence on enterprise endpoints is often unusual and should be investigated to determine intent, scope, and any associated malicious behavior.
+data_source:
+  - CrowdStrike ProcessRollup2
+  - Sysmon EventID 1
+  - Windows Event Log Security 4688
+search: |
+  | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime
+    from datamodel=Endpoint.Processes where
+    (
+      Processes.process_name = "tor.exe"
+      OR
+      (
+        Processes.process_path = "*\\BraveSoftware\\Brave-Browser*"
+        Processes.process_path = "*\\tor-*"
+      )
+    )
+    by Processes.action Processes.dest Processes.original_file_name
+       Processes.parent_process Processes.parent_process_exec
+       Processes.parent_process_guid Processes.parent_process_id
+       Processes.parent_process_name Processes.parent_process_path
+       Processes.process Processes.process_exec Processes.process_guid
+       Processes.process_hash Processes.process_id Processes.process_integrity_level
+       Processes.process_name Processes.process_path Processes.user
+       Processes.user_id Processes.vendor_product
+  | `drop_dm_object_name(Processes)`
+  | `security_content_ctime(firstTime)`
+  | `security_content_ctime(lastTime)`
+  | `windows_tor_client_execution_filter`
+how_to_implement: |
+  The detection is based on data that originates from Endpoint Detection
+  and Response (EDR) agents. These agents are designed to provide security-related
+  telemetry from the endpoints where the agent is installed. To implement this search,
+  you must ingest logs that contain the process GUID, process name, and parent process.
+  Additionally, you must ingest complete command-line executions. These logs must
+  be processed using the appropriate Splunk Technology Add-ons that are specific to
+  the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint`
+  data model. Use the Splunk Common Information Model (CIM) to normalize the field
+  names and speed up the data modeling process.
+known_false_positives: |
+  This detection focuses on TOR-related processes and may generate benign matches in environments where TOR is intentionally used, such as security testing, research, or lab environments.
+references:
+  - https://unit42.paloaltonetworks.com/tor-traffic-enterprise-networks/
+  - https://attack.mitre.org/software/S0183/
+  - https://attack.mitre.org/techniques/T1090/003/
+drilldown_searches:
+  - name: View the detection results for - "$user$" and "$dest$"
+    search: '%original_detection_search% | search  user = "$user$" dest = "$dest$"'
+    earliest_offset: $info_min_time$
+    latest_offset: $info_max_time$
+  - name: View risk events for the last 7 days for - "$user$" and "$dest$"
+    search:
+      '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$",
+      "$dest$") starthoursago=168  | stats count min(_time) as firstTime max(_time)
+      as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk
+      Message" values(analyticstories) as "Analytic Stories" values(annotations._all)
+      as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics"
+      by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
+    earliest_offset: $info_min_time$
+    latest_offset: $info_max_time$
+rba:
+  message: TOR client process $process_name$ was launched by parent process $parent_process_name$ on host $dest$ by the user $user$ with command line $process$
+  risk_objects:
+    - field: dest
+      type: system
+      score: 40
+    - field: user
+      type: user
+      score: 40
+  threat_objects:
+    - field: parent_process_name
+      type: parent_process_name
+    - field: process_name
+      type: process_name
+    - field: process
+      type: process
+tags:
+  analytic_story:
+    - Compromised Windows Host
+    - Windows Post-Exploitation
+    - Command And Control
+    - Data Exfiltration
+    - Data Protection
+  asset_type: Endpoint
+  mitre_attack_id:
+    - T1090.003
+  product:
+    - Splunk Enterprise
+    - Splunk Enterprise Security
+    - Splunk Cloud
+  security_domain: endpoint
+tests:
+  - name: True Positive Test
+    attack_data:
+    - data: https://media.githubusercontent.com/media/splunk/attack_data/refs/heads/master/datasets/attack_techniques/T1090.003/windows_tor_client_execution/windows-sysmon.log
+      sourcetype: XmlWinEventLog
+      source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational